Interception of the messages in transit would be INSANELY COOL (also siegers trying to snipe them, maybe this is what makes bats so useful as you can send them via the caverns if they are connected or they are trained to leave via a natural cave).
Of a greater concern than enemy snipers is the possibility of messenger creatures trying to fly through Evil weather, especially given the current level of the AI, which would doubtless generate an incoming pigeon right in the middle of a cloud of haunting fog. And yes, the player should be able to check all discovered caverns for off-map access to a surface cave, in much the same manner that we can check whether a Trade Depot has a wagon-pathable route. Caverns that connect with any cave that reaches the surface would be viable routes for both merchant caravans and flyers (at least as far as pathing is concerned), while those that lack such access should be ignored for both of these purposes.
I'll also echo the "noble position" thought, with the idea that once your fortress has reached a certain level of stability & prosperity, the Outpost Liason stops coming & going with the caravan and becomes a permanent resident, requiring his own room & furniture. He keeps the bats, and is willing to use his Animal Caretaking/Training skills in other areas as well (should you require that), and also comes with some minor skills in Organizing / Record Keeping too, and will accept those official titles & duties as well, if you wish--but he won't act as your broker, due to the obvious conflict of interest.
I like this idea but I think you should be able to assign him any labor. You often see weird things in the civ screen, like Queen Farmer and General Thresher. In a population of 200 or less, realistically everyone would have to work
Sure, everyone should work . . .
except pompous nobles living in your city by a direct order of the monarch himself, commanded to advise and oversee all diplomatic, economic, and migratory relations between the Mountainhome and your little barony . . . sent to advise and oversee and
that's it. He doesn't have to lift a damn finger if he doesn't want to. Now, you're right, any true dwarf
would want to, but because this guy has a "Noble from the Mountainhome" reputation to uphold, he can't get his hands dirty. There must be no Outpost Liaison/Ditchdigger (just as I imagine the Queen/Farmer and General/Thresher positions won't last long). That's why I had him open to accepting the tasks of
other nobles in the fort, and possibly other, "elite, dignified" jobs as well, like Gem Setting. Perhaps it would be best if the dwarf sent to be your fort's permanent Outpost Liaison had some appreciable amount of skill in one of these "cushy" jobs, & that particular labor turned on--and
you cannot change their allowed labors, because after all, the liaison is not one of
your dwarves.
Why does This have to be limited to messages? Like that old joke of how embarksing works, a roc very well would be able to carry and drop a wagon of supplies at a designated poijnt on demand, and having that be a way to deliver that from the mountainhome to some remote outpost on the other side of the world would be incredible.
Well, the game isn't called Roc Fortress. The fact that other civilizations exist, some of whom are likely at
war with your own nation, is because your civ
doesn't have a very obedient trained roc, willing to incendiary-bomb all other countries out of existence with magma-filled minecarts. I'd prefer to see this limited to messages. Some of those messages might call for emergency deliveries of supplies, sure, I'm all for that--but the actual goods would still have to be delivered by walking, talking sentients.
Naturally, an African Swallow should be able to carry more than a European Swallow. But if you get two European Swallows and tie a line between them it should come out to about the same value.
The flying ({copper arrow}) strikes the Carrier Swallow (Tame) in the right dorsal guiding feather, bruising the pinion!
The Carrier Swallow (Tame) loses hold of the -whip vine strand-.
The Carrier Swallow (Tame) loses hold of the (coconut).
Carrier Swallow (Tame) cancels Homing Carry: Cargo lost or destroyed.
Actually, using pigeons/bats for e.g. asking the Mountainhome for a military support in case of goblin siege would be incredibly wonderful. That would also require some sort of inter-civ politics . . . Be either an unimportant outpost or a wealthy pain in the arse and no one will care about you being slain. Also, the Mountainhome should be able to ask a military help from you.
Just so. Providing that your embark spot is close enough to your Mountainhome that an army could feasibly travel that distance in time to break the siege, this is an obvious candidate for the types of messages that could be sent. In
both directions, tit for tat & all.
Bonus points for making a truce with elves, then assigning the ambassador into a royal quarters made of wood, with wooden furniture and glass windows leading into torture pits where the elven slaves from the earlier sieges still suffer.
Anti-Elven sentiments aside, the release of prisoners would almost certainly be a condition of good diplomatic relations . . . although perhaps not an
absolute requirement for housing an ambassador, maybe the ambassador could be allowed to ransom a certain number of them free each year. Yes, the diplomat should be sensitive to things likely intended to deliberately give offense, so torturing them should be the best way to start a most spectacular war.
What about owls?
Yes. And hawks, falcons, and possibly seagulls. Underwater, I'd go with dolphins & sea turtles, but no fish. I think the idea of
training a fish is stretching credulity a bit too far.
"Leave him alone!" said Thorin. "The thrushes are good and friendly . . . The Men of Dale used to have the trick of understanding their language, and used them for messengers to fly to the Men of the Lake and elsewhere."
"I only wish he was a raven!" said Balin.
"I thought you did not like them! You seemed very shy of them, when we came this way before."
"Those were crows! And nasty suspicious-looking creatures they were, and rude as well. You must have heard the ugly names they were calling after us. But the ravens are different. There used to be great friendship between them and the people of Thror; and they often brought us secret news, and were rewarded with such bright things as they coveted to hide in their dwellings."
Perhaps you could have a container, like some bottle, to put the paper in.
Similarly-sized bivalve shells, sealed with wax. And dwarves already make glass vials. But I wouldn't mind if the container's existence was merely implied, leaving us to simply assume that if the message and its carrier are ready to go, then the container must exist as well. And I agree, paper is not strictly required, although it does seem the easiest, fastest, and most lightweight method. (I'm discounting the possibility of parrots & other talking birds actually
verbalizing the message at the receiving end, because of the time it would take to train the bird to accurately repeat that ONE specific phrase, which likely couldn't even be longer than a few seconds.)